When Salesforce Tower in San Francisco fully reopens this year after 16 months of pandemic-induced closure, one of its more unusual features will be found in the basement.
A series of pipes and cast-in-concrete holding tanks, arrayed on two levels in the parking garage like some hidden microbrewery, will take the dirty water generated by the structure’s daily operations through a six-step filtration process and return it as clean, nonpotable water for use in toilets and drip irrigation.
Taking up the space of 16 cars, the black-water system, so called because it treats all wastewater, including from toilets and showers, will filter an estimated 30,000 gallons per workday, or 7.8 million a year. The system, the most comprehensive of its kind in a high-rise tower in the nation, is designed for people to visit — each step of the process is labeled, said Amanda von Almen, head of sustainable built environment at Salesforce.
It’s also intended to help the company meet its goal of slashing corporate water use in half. “San Francisco’s our home, and there’s a drought here,” von Almen said. “We have to do something about it.”
The water-recycling effort is gaining traction as a severe drought punishes industries in states like California, Montana, New Mexico and Utah.
The concept isn’t new, but it’s increasingly seen as a promising sustainability push, especially as more cities and states enact measures to limit water use, and as a smart hedge against rising water costs and future shortages.
Park Habitat, an office tower that will include a black-water recycling system when it is built in downtown San Jose, Calif., is made for a world where droughts are an everyday reality, said Andrew Jacobson, head of development for Westbank, the project’s developer.
Water-conservation advocates say such technology is where solar and renewable power were a decade ago: technologically feasible, with pioneering projects starting to bend the cost curve and push the concept toward wider accessibility.
“Ten or 15 years ago, a green building was a ‘nice to have,’ whereas now it’s driven by regulations and the market,” said Aaron Tartakovsky, a co-founder and the CEO of Epic Cleantec, a wastewater tech startup in San Francisco. “It’s undeniable that the drought has accelerated conversations many were already having.”
Industrial water use has long been a corporate focus. Reducing the water bill for manufacturing, or for cooling data centers, has great value in terms of resilience, sustainability and reputation. But increasingly, commercial real estate is another way to cut water use, decrease resource dependency and promote green bona fides.
Commercial real estate is “where the balance of the pendulum” is for water conservation, said Paul O’Callaghan, founder of BlueTech Research and a co-producer of the 2020 documentary Brave Blue World: Racing to Solve Our Water Crisis. Roughly a third of the water use in San Francisco, for instance, takes place in commercial buildings.
Much of the technology behind water reuse is long established and relatively easy to install and operate, but it requires that local regulations catch up.
“A few cities, like San Francisco, Los Angeles, New York City and Boston, are creating the regulatory frameworks to expand this technology,” Tartakovsky said. “But now, states like Hawaii and Washington are looking to create systems that model what San Francisco did.”
Salesforce installed the black-water system primarily to demonstrate leadership on the issue, said von Almen, who declined to specify costs or savings figures. But there is long-term payback, especially if the cost of water rises over time.
Increasingly, developers see value in black-water systems, especially at scale, to provide water for irrigation and cooling towers. Even the cost to retrofit a building, long considered infeasible because of the need to add so many pipes for recycled water, is now more viable, Tartakovsky said.
$2.5 billion multiuse waterfront project led by the San Francisco Giants and developed by Tishman Speyer, will use a black-water system. Every building on the site, which broke ground this year, will tie into it over time. A new nonprofit utility, Mission Rock Utilities, will build and manage both it and a central thermal energy system.
Other cities have been looking at changing their infrastructure requirements to encourage or even mandate more water reuse in commercial structures.
San Francisco has been at the forefront of water conservation. A 2012 ordinance established standards for reuse, and it was updated in 2015 to require new buildings larger than 250,000 square feet to collect, treat and use gray water, a term for wastewater minus toilet waste.
Rafael Mandelman, a member of the city’s board of supervisors, has proposed doubling the amount of water that new buildings need to collect and reuse, and including buildings of 100,000 square feet or more.
An analysis in Austin, Texas, predicted the number of water customers in the fast-growing state capital would quadruple in 100 years. To meet some of that demand, the city offers incentives for developers to install reuse systems, and it plans to eventually make them mandatory.
“It’s a paradigm shift, seeing building owners bring their own water to the table, so to speak,” said Katherine Jashinski, a supervising engineer for Austin focused on on-site water reuse programs. “Companies moving here from California are interested in sustainability and want to make sure there will be a secure water supply.”
Cutting-edge examples will include even more resource and energy savings. In San Francisco, a system that Epic Cleantec will install in a proposed 55-story mixed-use development called 10SVN will recycle not just black water, saving an estimated
$12 million over the first decade, but also solids in the waste stream into organic soil. It will even recover and reuse the heat energy from wastewater.
“Wastewater isn’t really waste at all,” Tartakovsky of Epic Cleantec said. “It’s clean water, it’s organics, it’s nutrients, it’s energy we can redistribute, ultimately resulting in no waste at all.”